1. Field of the Invention
The present invention relates to a traffic analyzer for trunk or toll circuit switching facilities which analyzes both pulse code signalling, often referred to as decimal code because call dialing is transmitted in decimal code, and multifrequency code signalling.
2. Description of the Prior Art
It is known that the latter signalling code offers two advantages:
IT IS QUICKER THAN THE PULSE DECIMAL CODE; IN FACT, IT IS A PARALLEL CODE AND NOT A SERIES CODE;
IT CAN GIVE MUCH MORE DATA ON VARIOUS CALL ROUTING STEPS AND THIS IS IMPORTANT FOR TRAFFIC MONITORING.
Reception of multifrequency (MF) signalling requires multifrequency signalling receivers or siccintly multifrequency receivers (MFR) which are complex and costly. Due to the complexity and cost of such multifrequency receivers, it would be quite difficult to assign a multifrequency receiver to each trunk circuit to be monitored, and a feature of the present invention is that the number of multifrequency receivers is inferior to that of the monitored trunk circuits. Therefore, it becomes necessary that multifrequency receivers be connected to and disconnected from trunk circuits at proper instants, i.e. connected as soon as multifrequency signalling starts, and disconnected as soon as such multifrequency signalling ceases so as multifrequency receivers be released for availability to other trunk circuits.
The determination of the time during which a multifrequency receiver should remain connected varies because the number of MF digits of a multifrequency signalling call also varies and the multifrequency receiver can only be disconnected after the last MF digit has been received. However, this last digit can be deduced only from the sequencing or catenation of successive phases of the multifrequency code and from the combinations of code used in such phases.